A variety of technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture, molten salt power plants and artificial photosynthesis are used to capture the sun’s radiant light and heat for use in energy production.
Because of the way it captures and distributes solar energy or converts it into solar electricity, it is a vital renewable solar energy source.
The utilization of photovoltaic systems, concentrated solar electricity and solar water heating are all examples of active solar approaches. Techniques for passive solar include orienting a structure towards the Sun, selecting materials with favorable thermal mass or light-dispersing qualities, and designing spaces that naturally circulate the air.
Since solar energy is so abundant, it is a very attractive source of electricity. According to the United Nations Development Program’s 2000 World Energy Assessment, solar energy has a potential of 1,575 to 49,837 exajoules per year (EJ). In 2012, the world’s energy usage was 559.8 EJ, which is a huge difference!
Solar energy systems that are economical, unrenewable and clean will have enormous long-term benefits, according to the International Energy Agency in 2011. Through the use of an indigenous, inexhaustible, and largely import-independent energy source, it will increase energy security for countries, improve sustainability and reduce pollution, as well as lower the costs of mitigating global warming and keep fossil fuel prices lower than they would otherwise be. These are global advantages. Defined as learning investments, the increased expenses of early deployment incentives need to be intelligently spent and widely distributed.
The upper atmosphere gets 174 petawatts (PW) of solar radiation (insolation). The remaining 70% is absorbed by clouds, oceans and land masses. The visible and near-infrared portions of the solar spectrum are the most prevalent at Earth’s surface, with a small portion in the near-ultraviolet. About 3.5–7.0 kWh/m2/day is the average daily insolation for most of the world’s population, which ranges from 150 to 300 Watts/m2.
Terrain, oceans (which make up around 71 percent of the world), and the atmosphere absorb solar energy.
During convection, warm air that contains evaporating ocean water rises. Clouds form at high altitudes, when the temperature is low, and the condensed water vapor precipitates down to complete the water cycle. Convection is amplified by the latent heat of water condensation, resulting in wind, cyclones, and anticyclones. Seas and land masses absorb sunlight, keeping the Earth’s average surface temperature at 14°C. Green plants transform solar energy into chemically stored energy through photosynthesis, which generates food, wood, and the biomass from which fossil fuels are generated, as well as oxygen and nitrogen.
There are roughly 3,850,000 exajoules (EJ) each year of solar energy that the atmosphere, ocean and land masses of Earth absorb. As of 2002, the world consumed more energy in an hour than it did in a year. As a result of photosynthesis, approximately 3,000 EJ per year are stored in biomass. So much solar energy reaches our planet in a year that it is nearly twice as much as all of Earth’s non-renewable fossil fuels combined, including coal, oil, natural gas, and mined uranium.
Due to considerations such as geography, time variation, cloud cover, and area available to humans, we are limited in how much solar energy we can gather.
Geography has an impact on solar energy potential since locations closer to the equator receive more solar radiation than those farther away. For places that are further from the equator, photovoltaic systems that are able to track the Sun’s position can considerably boost solar energy potential.
For places that are further from the equator, photovoltaic systems that are able to track the Sun’s position can considerably boost solar energy potential. Due to the fact that the Earth’s surface receives very little solar radiation while it is dark, the potential of solar energy is affected by time variations. So, solar panels can only absorb so much energy in one day. This is because clouds obscure the Sun’s rays and lower the amount of light available to the solar cells.
Depending on how they capture, convert and disperse sunlight, solar technologies can be classified as passive or active, and they enable solar energy to be harnessed at different levels around the world, most of which are dependent on distance from the equator. All renewable sources of energy, excluding geothermal and tidal, obtain their energy either directly or indirectly from the sun.
Photovoltaics, concentrated solar power, solar thermal collectors, pumps, and fans are some of the active solar technologies that transform sunlight into useful outputs. It’s possible to use passive solar techniques by choosing materials with good thermal qualities, constructing rooms that naturally circulate air, and considering a building’s orientation in relation to the sun. Technologies that boost energy supply are called supply-side technologies, while those that lessen the need for alternative energy sources are known as demand-side technologies.
UN Development Program, Department of Economic and Social Affairs, and World Energy Council produced a report in 2000 that estimated the amount of solar energy that humans could utilize each year based on criteria such as insolation, cloud cover, and the amount of land that could be used by people. An estimated 1,600 – 49,800 exajoules (4.41014 – 1.41016 kWh) of solar energy can be harvested globally each year.
Thermal energy in Pakistan
Technologies based on solar thermal energy can be used for water heating, space heating, space cooling, and process heat generation among other things.
In 1878, Augustin Mouchot successfully displayed a solar steam engine at the Universal Exposition in Paris, but was unable to continue research due of cheap coal and other issues.
1917 Shuman’s solar collector patent drawing When Frank Shuman created a modest demonstration solar engine in 1897 using ether (which has a lower boiling point than water) and black pipes, it revolutionized solar energy in the United States.
With the goal of creating larger solar power facilities, Shuman founded the Sun Power Company in 1908. Using mirrors to reflect solar energy onto collection boxes, he created a better technique with his technical advisor A.S.E. Ackermann and British physicist Sir Charles Vernon Boys, which allowed for water to be used instead of ether. Using a low-pressure steam engine, Shuman was able to patent the entire solar engine system in 1912.
Maadi, Egypt’s first solar thermal power station, was developed by Shuman during the years 1912 and 1913.
As a result of this, a 45–52-kilowatt (60–70-hp) engine was used to pump water from the Nile River to nearby cotton fields at a rate of 22,000 litres (4,800 imp gal; 5,800 US gal) per minute. A new interest in solar thermal energy revived Shuman’s vision and fundamental design after World War I and the discovery of inexpensive oil in the 1930s. According to a 1916 media report, Shuman advocated solar energy usage, saying:
Solar energy has been proven to be profitable in the tropics, and we’ve shown that after our oil and coal reserves are depleted, the human race will be able to harness the sun’s beams indefinitely.
water heating in Pakistan by Solar energy
Solar hot water systems heat water by using the sun’s energy. Between 40 degrees north and 40 degrees south, solar heating systems may provide 60 to 70 percent of residential hot water, with water temperatures up to 60 °C (140 °F). Vacuum tube collectors (44 percent) and glazed flat plate collectors (34 percent) are the most prevalent types of solar water heaters for home hot water.
About 436 thermal gigawatts (GWth) of solar hot water systems were installed worldwide in 2015, with China leading the way with 309 GWth, or 71% of the market. Over 90% of households in Israel and Cyprus have solar hot water systems. In the United States, Canada, and Australia, solar hot water is mostly used to heat swimming pools, with an installed capacity of 18 GWth as of 2005 in the United States, Canada, and Australia.
Heizung, Ventilation and Air Conditioning (HVAC) systems account for 30 percent (4.65 EJ/yr) of the energy used in commercial buildings, and over 50 percent (10.1 EJ/yr) of the energy used in residential structures, in the United States This energy can be countered in part by solar heating, cooling, and ventilation systems.
When it comes to thermal mass, it’s everything that can store heat. In the case of solar energy, the sun’s heat is used to generate electricity. Materials that are commonly used as thermal mass include stone, cement, and water. Arid areas or warm temperate regions have traditionally utilized them to keep buildings cool by absorbing solar energy during the day and releasing stored heat to colder atmosphere at night.
In colder climates, though, they can also be used to keep warm. Many elements such as climate, daylighting, and shading conditions affect the size and positioning of thermal mass. Thermal mass, when properly implemented, helps to keep indoor temperatures within a reasonable range and lowers the need for auxiliary heating and cooling equipment in buildings.
As the name suggests, a solar chimney (or thermal chimney) is a passive solar ventilation system consisting of a vertical shaft that connects the interior and exterior of a structure. Heat from the chimney causes an updraft, which draws air through the building as the chimney gets warmer.
To boost performance, utilize glass and thermal mass materials in a greenhouse-like fashion.
There has been a push for the use of deciduous trees and plants as a technique of managing solar heating and cooling. Planting them on the southern side of a structure in the northern hemisphere, or on the northern side in the southern hemisphere, will provide shade in the summer and allow light to pass through during the winter.
But they can be employed on the east and west sides to provide a degree of summer shade without lowering winter solar gain significantly.
Molten salt technology by solar energy in Pakistan
For example, concentrated solar power plants that use solar towers or troughs can use liquid sodium to store thermal energy so that it can be used to create electricity in inclement weather or at night. From 1995 to 1999, it was shown in the Solar Two project. Rather than converting heat directly into electricity, the system is anticipated to have a 99 percent yearly efficiency. The molten salt mixes might be rather different.
When the salt melts, it does so at a temperature of 131 degrees Celsius (268 degrees F). In an insulated “cold” storage tank, it is kept liquid at 288°C (550°F). Through solar collector panels, the salt is heated to 566 degrees Fahrenheit. In the end, it is stored in a hot tank. This is so thoroughly insulated that it can store thermal energy for up to a week.
To generate electricity, hot salt is delivered to an ordinary steam-generator, which produces superheated steam for a turbine/generator similar to those in a coal, oil or nuclear power station. According to this design, a 100-megawatt turbine would require a tank 9.1 meters tall and 24 meters in diameter to run for four hours.
Electricity production by solar energy in Pakistan
Using photovoltaics (PV) or concentrated solar power, solar power converts sunlight into electricity (CSP). A vast area of light is focused into a narrow beam using lenses or mirrors and tracking technologies. Using the photoelectric effect, PV turns light into electric current.
By 2050, solar photovoltaics and concentrated solar power are expected to account for 16 and 11 percent of worldwide electricity consumption, respectively. Solar power generated 1.3 percent of the world’s electricity in 2016, following another year of strong development.
In the 1980s, the first commercial concentrated solar power facilities were constructed. California’s Ivanpah Solar Power Facility, with a capacity of 392 megawatts, is the world’s largest solar power facility. Also in Spain are the 150-MW Solnova Solar Power Station and the 100-MW Andasol Solar Power Station, both of which have a capacity of 100 megawatts. Largest photovoltaic facilities in the world include the 250 MW Agua Caliente Solar Project in the United States and the 221 MW Charanka Solar Park in India Even though solar projects over 1 GW are in the works, most are modest rooftop photovoltaic arrays of less than 5 kW, which are connected to the grid via net metering
It has taken photovoltaics (PV), also known as solar PV, during the last two decades for it to move from the niche market of small-scale applications to a mainstream energy source. By exploiting the photoelectric effect, a solar cell transforms light into electricity. As early as 1880, Charles Fritts created the first solar cell. For the first time, a photo cell was created utilizing silver selenide instead of copper oxide by German engineer Dr Bruno Lange in 1931 Ernst Werner von Siemens and James Clerk Maxwell realized the significance of this finding, even though the prototype selenium cells converted less than 1% of the incident light into electricity.
Gerald Pearson, Calvin Fuller, and Daryl Chapin, following Russell Ohl’s work in the 1940s, invented the crystalline silicon solar cell in 1954. A 4.5–6 percent efficiency was achieved with these early solar cells, which cost US$286/watt By 2012, accessible efficiencies had surpassed 20 percent, while the greatest efficiency of research photovoltaics had surpassed forty percent.